This UCLA Symposium will address animal models of human viral diseases and their relevance to the development of human therapeutics. The AIDS epidemic has led to renewed emphasis on understanding the pathogenesis and control of viral infections in man. Recent advances in transgenic animals are but one example of exciting new approaches to developing models in which therapeutic strategies aimed at human viral diseases can be tested. It is clear from the relatively small armamentarium available to the clinician that the development of therapeutic modalities lags considerably behind the rather impressive recent advances in elucidating the replication and pathogenesis of viruses at the cellular and subcellular levels. The development of prophylactic and therapeutic interventions for viral diseases requires the extensive use of animal models. The results of animal model research, however, are not always predictive of clinical response. Recent advances in the understanding of disease pathogenesis of animal models and their implications for the development of antiviral therapies and vaccines will be discussed.